The Move To Copper-Nickel Tubing Copper had been proved since the early days to have many good attributes. It was easy to bend and had very high corrosion resistance, but there was concern about its low corrosion-fatigue strength. When copper-nickel was introduced, it displayed corrosion resistance similar to copper, higher general strength and better fatigue strength. Good formability allows ease of flaring and bending, and although the metal cost is greater than that of steel alternatives, copper-nickel is very attractive in view of its extra life, trouble-free installation and safety/reliability
Characteristics. Properties of Copper-Nickel Brake Tubing
The copper-nickel alloy used for brake tubing typically contains 10% nickel, with iron and manganese additions of 1.4% and 0.8% respectively. The product conforms to ASTM B466 (American Society for Testing and Materials), which specifies dimensions, tensile strength and yield strength. Formability and internal cleanliness conform to specifications SAE J527, ASTM A254 and SMMT C5B (Society of Motor Manufacturers and Traders). Also, the alloy meets the requirements for pressure containment, fabrication and corrosion resistance for ISO 4038 (International Standards Organization) and SAE J1047.
The mechanical properties of alloy C70600 in comparison with steel and copper are shown in
| Dimension Tolerance |
| Material | Ultimate Tensile Strength1000 psi (MPa) | Yield Strength 0.5% Ext.under Load 1000 psi (MPa) | YElongation % in 2 in. | Fatigue Strength (10x7 cycles) 1000 psi (MPa) | Burst Pressure* 1000 psi (MPa) |
| Copper-brazed Steel | 48-55 (0.330-0.380) | 28-34 (0.190-0.235) | 30-40 | 30 (0.210) | 19.5 (0.135) |
| C12200-Phosphorus deoxidized Copper | 32-38 (0.220-0.265) | 10-14 (0.070-0.100) | 45-60 | 10 (0.070) | 12 (0.083) |
| C70600-Copper Nickel 90-10 | 48-54 (0.330-0.370) | 16-22 (0.110-0.150) | 40-55 | 15 (0.100) | 19 (0.130) |
Alloy C70600 is normally supplied as redrawn tubing in the annealed condition. The combination of strength and good ductility give excellent formability.
As copper-nickel is softer than steel, it was first feared that fretting might be a problem. Experience has shown this is not the case.
